The present invention relates to a wood bit for boring holes in wood or similar materials. Wood bits generally have a central point and a spade shaped blade or cutting section attached to a shaft, wherein the bit is usually driven by some type of power tool.
Wood bits known in the art utilize blades of various shapes and sizes, some incorporating spurs on the outside edges of the shoulders to provide better penetration of the blade into the wood substrate. Often the blades of wood bits include flutes ground into the surface of the cutting blade face along the shoulder or tip to enhance the cutting effect and provide better deflection of the wood chips from the bore. Conventional methods of forming flutes or grooves into the blade face utilize grinding processes which cut into the blade surface, thereby decreasing the thickness of the blade in the area of the groove, and forming a deflection surface within the blade face so that chips must be deflected at a sharp, acute angle formed by the outer surface of the flute joining the inner surface of the flute. Usually the cutting edges are formed on the leading end of the blade separated from the flutes. These conventional wood bits are usually flat, having cutting edges which do not project outward pass the plane of the blade face.
For example, the Williams III, U.S. Pat. No. 4,682,917 describes a wood bit designed having a flute ground into the blade face extending from the tip and along the lateral shoulder portion of the blade, stopping where the rake of the shoulder spur intersects the shoulder flute. The leading cutting edges of the blade remain level with, or recessed within the face of the blade.
The chip deflection means of the present invention is designed to be manufactured in a one step bending process simplifying and reducing the expense of a milling and/or grinding step to cut the desired flute pattern into the blade surface. The chip removal means of the present invention does not utilize a flute formed at an acute angle such as used in the Williams III bit, but rather utilizes a forging process to bend a continuous hook into the leading end of the blade extending along the lateral shoulders and converging in a central point. Wood shavings are directed upwardly onto the blade surface at an obtuse angle rather than an acute angle as taught in the William's reference in order to provide more efficient removal of the chip debris from the cutting surface. The leading end of the blade, including the hook is of generally uniform thickness. The design of the hook projecting beyond or outwardly (in the direction of rotation) pass the plane of the blade surface and along the lateral shoulder and central point maximizes the strength and long life of the cutting edges of the blade while the forging process minimizes waste material formed during the manufacture of the wood bit.
Although several different types of wood bits are commercially available, there exists a need to provide a wood bit which is characterized by having good penetrability, durability, and is inexpensive to manufacture.
Accordingly, it is an object of the present invention to provide a novel and improved wood bit having good penetrability and durability.
It is an object of the present invention to provide a wood bit with a spade shaped blade having an improved cutting edge utilizing cutting spurs on the corners of the blade.
Furthermore, it is another object of the present invention to provide the advantages of better chip flow through the use of an obtuse hook angle formed by a forging process to bend the leading end of the blade in opposite directions (in the direction of rotation) on each side of the blade axis, and to extend the leading end of the blade beyond the plane of the blade surface, forming a hook extending continuously from the side of the blade along the lateral shoulder to the central point, whereby the leading end of the hook projects beyond or outwardly of (in the direction of rotation) the plane of the blade surface.
It is yet another object of the present invention to provide a wood bit having beveled cutting edges extending continuously along the leading edge of the hook of the blade from the side edge of the blade through the cutting spur, along the lateral shoulder, and terminating at a central point to provide high performance at a low cost.
Finally, it is an object of the present invention to manufacture a wood bit by a method requiring fewer process steps so that the wood bit can be manufactured and sold at a lower price to a wide range of commercial and home markets users.